It happened to me so much I just got fed up with it and brought it back to Best Buy and exchanged for a new one and the dam thing still does it so it's eitehr the game itself or my PS3. Hope a patch is comming
Any help would be greatly appriciated
EDIT: If you sign off of the PSN before you start gta it will load fine. Theres something wrong with the servers right now thats causing the freezing even loading the single player. Rumors are that they are ramping up the servers on Monday so hope it's true. Again sign off the PSN then start game without being signed in and you will be able to play single player. If you want to try signing in from your cellphone it works sometimes too.